Mean pulmonary venous pressure (= LAP = [[2023-NOV-GM#Pulmonary capillary wedge position and pressure| Wedge Pressure]]) = 5mmHg.

• Absence of phaeochromocytoma or myocarditis.

| Phentolamine | Non selective alpha adrenergic blocker; | Used in catecholamine induced hypertension (phaeochromocytoma, tyramine ingestion in patient on MAOI |

Pulmonary capillary wedge position and pressure (PCWP)

#2023GM-NOV/Q02
Pressure transduced catheter is introduced into the femoral or jugular vein.

Basic Science

Source

• Then advanced through SVC/ IVC -> right atrium -> Right ventricle -> Pulmonary artery -> Left or right branch PA.
• Position can be confirmed by the pressure tracing in each position.
• Inflation of the balloon blocks off the branch PA -> after a few seconds, pressure distal to the balloon approximates left atrial pressure.
• Ideally, the catheter tip should be in an arterial segment supplying a "[[2018-OCT-BSQ#Pulmonary vascular resistance|Zone 3]]" region of the lung. (Alveolar pressure is less than PA and PV pressure so that blood stream from PA to PV is uninterrupted -> pressure is transmitted from LA to catheter port)

Clinical context

• Clinical Use:
  • Diagnosis of severity of left ventricular failure
  • quantify degree of mitral valve stenosis
  • AS, AR, MR also ⬆ LA Pressure
  • Measurement of cardiac output by thermodilution.
  • Calculation of pulmonary vascular resistance (based on measurement of pulmonary blood flow, pulmonary artery pressure and PCWP)
• Values: Pulmonary oedema likely above PCWP > 20mmHg.
• Complications: Pulmonary artery rupture from over inflation of the balloon.
• Pitfalls: Proper placement is essential for accurate results:
  • Placement is confirmed by Source
    • Presence of well defined a and v waves.
    • Fluoroscopic confirmation of position
    • Oxygen saturation > 90%
      • In the proper wedge position with complete occlusion, saturation should approximate left atrial saturation (i.e > 90%). Lower saturation indicates incomplete occlusion by the balloon. Source
    • Abrupt rise in mean pressure when the balloon is deflated.

Phaeochromocytoma